The Silver Medallion is an obtainable item in the first Silent Hill game. Harry Mason can find it in the second floor Music Room in Midwich Elementary School. It can only be picked up after solving the Piano Puzzle. After correctly pressing the piano keys in order, the silver medallion will inexplicably fall from the wall above the chalkboard where Harry can then pick it up.
Its purpose is to allow access to the clock tower in the school's courtyard. It, along with the Gold Medallion, unlocks the door to the clock tower and allows Harry entrance to the Otherworld version of the school.